Based on:
Subj: libbpf: Helpers to access XDP hints based on BTF definitions
https://lore.kernel.org/all/20210803010331.39453-15-ederson.desouza@intel.com/
From: Ederson de Souza <ederson.desouza@intel.com>
Ederson says:
A new set of functions to help get the BTF definition of XDP hints
structure and get the information based on it.
`xsk_umem__btf_id` helps retrieve the BTF id of XDP metadata.
`xsk_btf__init` sets up a context based on the BTF, including a hashmap,
so that subsequent queries are faster.
`xsk_btf__read` returns a pointer to the position in the XDP metadata
containing a given field.
`xsk_btf__has_field` checks the presence of a field in the BTF.
`xsk_btf__free` frees up the context.
Besides those, a macro `XSK_BTF_READ_INTO` acts as a convenient helper
to read the field contents into a given variable.
Note that currently, the hashmap used to speed-up offset location into
the BTF doesn't use the field name as a string as key to the hashmap. It
directly uses the pointer value instead, as it is expected that most of
time, field names will be addressed by a shared constant string residing
on read-only memory, thus saving some time. If this assumption is not
entirely true, this optimisation needs to be rethought (or discarded
altogether).
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
This USER_TARGETS_OBJS_DEPS allows makefiles to define
dependencies for USER_TARGETS_OBJS targets.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Jesper Dangaard Brouer
Ederson de Souza